Lifting jack



May 6, 1930. J. G. EVERSTAM LIFTING JACK Filed Dec. 24, 1925 [oxen/or: JOHHN Guam/m EVEfiST/IM Patented May 6, 1930 'QUNITED STATES PATENT. OFFICE] JOHAN GUNNAR nvnns'raivr, or SUNDSVALL, SWEDEN meme JACK Application filed December 24;, 1925, SerialNo. 77,578, and in Sweden August 18,1925.

I The present invention relates to a lifting some distance below the upper end of the jack of the type in which there is pivotally mounted in the frame of the lifting jack a le-' ver by the reci rocation of which to and frousually up an d0w nthe load is raised and lowered by the intermediary 0f a feeding pawl pivoted in the lever and which-engages a toothed rack slidable up and down'in the frame. In lifting jacks of this type as heretofore used, and which have been put to use particularly forlifting motor cars, the raising of the load is effected only whenthe lever is turned'in the one direction, usually downwards. This entails the disadvantage that-the raising of the load requires a comparatively long time, since after each active strokethe lever must be returned idle. I

The invention has for its purpose to avoid this disadvantage, and consists princip'ally'in' that two feeding pawls are pivoted in the lever on opposite sides of the fulcrum of said lever,'said pawls being adapted to engage a toothed rack or the like common to both pawls, and which is slidable in the frame and serves to carry the load, in such manner that saidtoothed rack is displaced upon movement of the lever injboth-directions. Since thus the lever need not be moved idle, the raising of the load may be effected considerably faster. 1

In the accompanying'drawingan embodiment of the invention is illustrated by way of example. Fig. 1 shows a'vertical section of a "lifting jack according to theinvention, and '35 Fig. 2 shows ahorizontal section of the jack on the line IIII inFig. 1. Figs 3 and 3 show the outer long feeding pawl, viewed from two difierent sides, and Figs. 1 and 4 show in similar manner the inner short pawl. Figs. 5 'and'5 show the lever in section and viewed from above respectively, and Figs. 6

and 6 show, viewed from two diflerent sides,

the switch lever which is common to both feeding pawls.

In the embodiment illustrated, 1 denotes the frame of the lifting jack in which the toothed rack 2 is movable vertically. The toothed rack 2 supports at its upper end the usual plate 3 which is intended to beplaced underneath the loadto be lifted, and also at with which two feeding pawls 6 and 7 engage, which are adapted to be actuated by means of a handle or the like which is intended to be introduced'in the outer sleeveshaped end *8 of a lever 9 pivoted on a pin 10 in the frame 1. 'The feeding pawls are pivoted in thelever 9 by means of pins 11 and12. The feeding pawls are actuated by springs" 19 and 20 which tend to turn the pawls to engage the toothed rack. As shown in, Fig. ,1, the fulcra or pins 11 and'12 of the feeding pawls are located on opposite sides of the fulcrum or pin 10 of the lever 9, so that when the lever 9 is turned for instance in the=coun- I I ter-clockwise direction 'inFig. 1, the inner v pawl 7 will be raised and the outer p'awl 6 will be lowered, whereas the outer pawl 6- will be raisedand the inner-pawl 7 lowered when'thelever 9 is turned in the opposite direction. When the feeding pawls areactuated only bythe springs 19 and 20 the toothed.

rack 2 willthus be moved upwards upon turning the lever 9 in both directions, the movement being. effected alternately by the one and f I the other feeding pawl.

In order to render it possible to lower'the toothed rack 2, as shown inFig..2, and coopcrate with a shoulder 15 on the switch lever 16 which is common to both arms. Said lever is pivoted on the pin 10 of the lever 9, at the side of said lever '9, and is actuated by a spring 17 which tends to maintain the switch lever in one of 'its two extreme positions. The switch lever 16 is provided at its outer end with a handle 18 by means of which it may be turned from one extreme position to the other. 7 Owing to the arms 13 and 14 andthe shoulder 15 for the same being located at the side of the toothed rack 2, as above described, the advantage is attained that the pins 11 and 12 of the two feeding pawls 6'and 7 may be located so close to the toothed-rack, that the 1 angle between the outer feeding pawl 6 and V the toothed rack 2 will in no case exceed 30 which, as demonstrated by tests, is a necessary condition for the mechanism operating quite satisfactory.

In the position of the different parts shown in Fig. 1, the switch lever 16 is set for lowering the load, the arm 13 ofthe outer pawl 6 bearing against the shoulder If new it is desired to lower the load, the lever}? is first turned slightly in the counter-clockwise direction in Fig. 1, with the" resu'l tthattlie pawl 6 is slightly lowered so that it becomes free from the load resting on the same, and by the action of the spring 17 and shoulder 15 it will arm 14 is also lowered and meets the shoulder 15 and. forces said shoulder slightly downwards. The res'ultis" that the outer pawl 6 may, under the actuation of its spring 19, move into engagement with a tooth Simmediately-f above the end of said-pawhand take over the load.- As'soon as this has taken place, the pawl 7 is turnedback out of, engagement with the toothed rack 2', in the same manner 7 35 as above described in respect of the pawl 6.

When afterwards the lever9 isagain turned in the counter-clockwise direction the outer pawl 6' lowered and thus also the toothed rack 2 and theload. The courseldescribed repeats itself as long as the switch lever 16 occupies the position shown in Fig." 1.

If it is desired again to raisethe load, the

switch lever 16 is turned by means of the handle 18 in the clockwise direction in Fig. 1 to its other extreme position,- in which the lever will be retained by the spring 17 as soonas said spring has passed its middle position. By said turningof the switch lever the shoulder 15 is lowered so far that it will not touch the arms 13- and'14 during the movements of the feeding pawls. jOon'seq5uently,the feeding pawls are nowonly actuated by the springs 19 and 20' which" tend to maintain said pawls in engagement withthe tio'tithed rack 2, and said pawls will therefore alternately operate to' raise the toothed rack, each pawl sliding over one tooth when it moves doivnward; 1 7

As shown, the ends or points of the feeding pawls 6 and 7 are rounded", and'the bottoms of the spaces between the teeth 5 of the toothed rack 2*are also rounded corres'pondifigly, for the purpose thatdurir'i-g the operation of'the rank the pawls shall" have a sliding engagement with the rack, and the load bedistributed over a large surface on the ends of the pawls. As shown in Figs. 6 and 6 the switch lever 16 is provided with a lug 21 with a hole 22 located approximately in the same vertical plane as the middle of the shoulder 15. In said hole 22 the spring 17 is introduced, and "it will thus act in subs'ta-ntia lly' the same planeas the arms 13 and 14 of the feeding pawls 6 and 7 when engag-' ing saidshoulder 15, any tendency of said arms-t6 tilt the switch lever sidewise on the pin 10 being thus counteracted.

The embodiment above described and illustrated in the drawing is only tobe regarded i Iclaim-z '1. In a lifting jack, the combinationof a frame, atoothed rack movable in said frame and adapted to support. the load, a lever pivoted in said frame, two feeding pawls pivoted to said lever on opposite sidesofthe fulcrum of said lever and adapted to engage said toothed rack, eachof said pawls'fbeing provided with a rigid arm, both saidoarms projecting forward to one and thesame side of said rack,- andan adjustable switch lever having a shoulder adapted in one position of adjustment of said switch lever; to cooperate with said rigid arms on said pawls to" move said pawlsalternatelyout of engagement with said rack duringthe operation of said pawls through said lever; Y

In a lifting jack, the combination of a frame, atoothed rack provided with arow of teeth on its front side and slidable in said frame and. adapted to support theload, a lever pivotedin said frame,- two feeding pawls pivoted to said lever on opposite sides of the fulcrum of said lever and adapted to engage said row of teeth onsaid toothed rack, each of said pawls being provided atone side with a rigid arm, both said. arms pro jecting forward to one andcthesame side of said rack, andan adjustable and spring-aetuated switch lever which also, projects forvward to said one side of the toothed rack and which has a shoulder adapted in one'p'osition of adjustment" of saidswitch lever to cooperatewi'thsaidrigid arms' on said pawls to movesa-iid. pawls alternately out of engagem'entwith said rack during the operation i ofsaid pawls through said lever.

3'. In a lifting jack; the combination of a frame, a toothed rack slidablei'n 'said frame and adapted to support the load-said rack having a row of teeth on its front side, a

lever pivoted said frame, two feeding pawls'pivoted to said lever on opposite sides of the fulcrum of said lever and adapted to engage said row of teeth on sa-idtoothed rack, each of said pawls being provided at one side with a rigid arm, both said arms projecting forward to one and the same side of said rack, a spring-actuated switch lever pivoted on the fulcrum of said first-mentioned lever,

said switch lever also projecting forward to 

